Java JComboBox ActionListener crash

Question

I'm getting

Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: -1

when I'm deleting last Item in JComboBox. Anyone knows why?

cb = new JComboBox<String>();
bComboDelete.addActionListener(this);

bComboDelete = new JButton("X"); //deletes item from CB
bComboAccept = new JButton("#");// add an item

ArrayList<String> names = new ArrayList<String>(); //get name, runs with sNumbers
ArrayList<String> sNumbers = new ArrayList<String>();//some String numbers ----> e.g.  [[1, 2, 3],[4, 5, 6]]
ArrayList<Integer> numbers = new ArrayList<Integer>(); //array to temp hold numbers

//***ending code from ActionListener
else if(s == bComboAccept)
{
    sNumbers.add(numbers.toString());
    //System.out.println(sNumbers);
    names.add(tName.getText());//tName is JTextField
    //cb.addItem(tName.getText());

    cb.addItem(new String(tName.getText()));
    cb.setSelectedItem(new String(tName.getText()));
}

else if(s == bComboDelete)
{
    int z = cb.getSelectedIndex();
    //System.out.println(z);
    names.remove(z);
    //System.out.println("Names: "+names);
    sNumbers.remove(z);
    //System.out.println("sNumbers: "+sNumbers);
    cb.removeItem(cb.getSelectedItem());

}

else if(s == cbLista)
{
    System.out.println("cb Action listener!\n--------------");

    Integer i = cb.getSelectedIndex();


    tNames.setText(nazwy.get(i));
    tNumbers.setText("");//also TextField

    numbers.clear();
    numbers=arrayStringToIntegerArrayList(sNumbers.get(i));
    tNumbers.setText(numbers.toString().substring(1, numbers.toString().length()-1));
}

Rest of crash code:

Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: -1 at java.util.ArrayList.elementData(Unknown Source) at java.util.ArrayList.get(Unknown Source) at Okno.actionPerformed(Okno.java:339) at javax.swing.JComboBox.fireActionEvent(Unknown Source) at javax.swing.JComboBox.contentsChanged(Unknown Source) at javax.swing.AbstractListModel.fireContentsChanged(Unknown Source) at javax.swing.DefaultComboBoxModel.setSelectedItem(Unknown Source) at javax.swing.DefaultComboBoxModel.removeElementAt(Unknown Source) at javax.swing.DefaultComboBoxModel.removeElement(Unknown Source) at javax.swing.JComboBox.removeItem(Unknown Source) at Okno.actionPerformed(Okno.java:328) at javax.swing.AbstractButton.fireActionPerformed(Unknown Source) at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source) at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source) at javax.swing.DefaultButtonModel.setPressed(Unknown Source) at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source) at java.awt.Component.processMouseEvent(Unknown Source) at javax.swing.JComponent.processMouseEvent(Unknown Source) at java.awt.Component.processEvent(Unknown Source) at java.awt.Container.processEvent(Unknown Source) at java.awt.Component.dispatchEventImpl(Unknown Source) at java.awt.Container.dispatchEventImpl(Unknown Source) at java.awt.Component.dispatchEvent(Unknown Source) at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source) at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source) at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source) at java.awt.Container.dispatchEventImpl(Unknown Source) at java.awt.Window.dispatchEventImpl(Unknown Source) at java.awt.Component.dispatchEvent(Unknown Source) at java.awt.EventQueue.dispatchEventImpl(Unknown Source) at java.awt.EventQueue.access$500(Unknown Source) at java.awt.EventQueue$3.run(Unknown Source) at java.awt.EventQueue$3.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at java.awt.EventQueue$4.run(Unknown Source) at java.awt.EventQueue$4.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at java.awt.EventQueue.dispatchEvent(Unknown Source) at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source) at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source) at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source) at java.awt.EventDispatchThread.pumpEvents(Unknown Source) at java.awt.EventDispatchThread.pumpEvents(Unknown Source) at java.awt.EventDispatchThread.run(Unknown Source)

Answer 1

It seems I fixed this. Now code is like this:

I'm too lazy to rename the var to eng. Please ignore System out.

so:

nazwy = names
oceny = numbers
sOceny = sNumbers
cbLista = cb
tNazwa = tNames
tOceny = tNumbers

//----
else if(s == bComboDelete)
    {
        Object o = cbLista.getSelectedItem();

            int z = nazwy.indexOf(o);
            if(z>-1)
            {
            sOceny.remove(z);
            nazwy.remove(z);
            cbLista.removeItemAt(z);
            System.out.println("Oceny w bloku delete(if)"+oceny.toString());
            }
            System.out.println("Oceny w bloku delete(poza if)"+oceny.toString());
    }

    else if(s == cbLista)
    {
        Object o = cbLista.getSelectedItem();

        int z = nazwy.indexOf(o);
        if(z>-1)
        {
        tNazwa.setText(nazwy.get(z));
        oceny.clear();
        oceny=arrayStringToIntegerArrayList(sOceny.get(z));
        tOceny.setText(oceny.toString().substring(1, oceny.toString().length()-1));
        System.out.println("Oceny w bloku CB"+oceny.toString());
        }
        else
        {
            tNazwa.setText("");
            tOceny.setText("");
            oceny.clear();
        }


    }

Answer 2

Try adding the following modifications...

else if(s == bComboDelete)
{
    int z = cb.getSelectedIndex();

    // -1 means that no item is selected
    if (z > -1) {
        //System.out.println(z);
        names.remove(z);
        //System.out.println("Names: "+names);
        sNumbers.remove(z);
        //System.out.println("sNumbers: "+sNumbers);
        cb.removeItem(cb.getSelectedItem());
    }
}
else if(s == cbLista)
{
    System.out.println("cb Action listener!\n--------------");

    Integer i = cb.getSelectedIndex();

    // -1 means that no item is selected
    if (i > -1) {
        tNames.setText(nazwy.get(i));
        tNumbers.setText("");//also TextField

        numbers.clear();
        numbers=arrayStringToIntegerArrayList(sNumbers.get(i));
        tNumbers.setText(numbers.toString().substring(1, numbers.toString().length()-1));
    }
}